1. Field of the Invention
The present invention relates to power supplies for supplying electrical power to a load. More specifically, the invention relates to a high-efficiency power supply including plural tank circuits whose function and interaction are controlled by a set of specially controlled switches and constant current controllers.
2. Related Art
Power supplies including charge storage eIements (or, more broadly, energy storage elements), are known in the art.
For example, U.S. Pat. No. 4,628,284 (Bruning) discloses a high-frequency, high-voltage supply involving switching of transistors for, for example, magnetrons of microwave ovens. A "dead time" is provided between the intervals when one or the other of the transistors is off.
U.S. Pat. No. 4,319,315 (Keeney, Jr. et al) discloses a DC-to-DC convertor with oppositely conducting transistor pairs.
U.S. Pat. No. 3,886,429 (Maillard et al) discloses a symmetrical power pack for adapting to different sources. The power pack provides for alternate blocking and saturation of pairs of switching transistors.
U.S. Pat. No. 4,748,311 (Thomas et al) discloses a chopper circuit having a push-pull frequency f.sub.O and parallel tuned circuit at 2xf.sub.O. A goal of the Thomas et al circuit is to reduce power loss in their switching means.
U.S. Pat. No. 4,542,440 (Chetty et al) discloses a current sensor involving two power switches and two associated snubber circuits which operate 180.degree. with respect to each other.
U.S. Pat. No. 5,513,226 (Josephson) discloses a ballast inverter circuit which comprises two tank circuits. The two tank circuits operate at a common resonant frequency. A pair of transistors are switched in opposition so as to operate in a push-pull manner.
U.S. Pat. No. 4,709,323 (Lien) discloses a parallel resonant converter in which resonant circuitry recovers energy which would otherwise be lost in the circuit's switching operation.
Efficiency of power supplies has been measured in terms of the amount of energy which is consumed internally, within the power supply itself. Of course, it is desirable to minimize the amount of energy which is consumed internally, as energy which is consumed internally cannot be delivered to the load.
There is always a need to provide power supplies having greater efficiency. The present invention fulfills this need.